There are actually heated lakes all over the place. Hyco just happens to have a great campground on its shores. Illinois has a few heated lakes--not sure how warm they stay. Check out Clinton Lake between Bloomington and Decatur--supposed to have nice camp grounds. There is also another heated lake in southern Illinois--heated by a power plant, just don't know the name.

lake sinclair georgia , 2 hours east of atlanta. 1 buk to park at ramp a day , can stay at local college town 5 miles down road. no one is at the lake that time of year except fishing , lake temp mid 70dish because of hydro plant on lake, i wear short or long suit depending on how hot the sun is pumping , its more for the wind chill then water chill.

I've been in at OWC in trunks in late february. You will standout as most locals are the ones in full wetsuits!!! Last year was cooler, and I bought a chillskin, which was awesome. I recommend checking with them about the Quality in. It was cheap and they had a happy hour from 5-7 as x-girl pointed out.